This invention relates to a method for selectively controlling growth of undesirable plants in an area containing growing undesirable plants and an established cereal crop which comprises applying to said area N-[2-(4(3,5-dichloro-2-pyridyloxy)phenoxy)propionyl]-(optionally alkyl substituted) isoxazolidine as described herein at a rate of application which controls growth of said undesirable plants and which does not significantly affect growth of said established cereal crop.
During the past years, there has been an intensified search for selective herbicides. While various useful substances have been developed, there is still need for agents which have a better balance of properties or which exhibit special properties. Some compounds are highly toxic to all types of plants and thus lack the selectivity and differential characteristics which are necessary for many applications. For example, a herbicide will exhibit excellent activity against undesirable grassy weeds. Frequently, because of this activity such a herbicide also elicits a phytotoxic response in desirable grass plants. In meeting the need for a selective herbicide having excellent safety toward desired plants, the present invention provides a significant advance.
From U.S. Pat. No. 4,447,259, it is known that 2-(substituted-phenoxy)propionic acid derivatives having the formula ##STR1##
R.sup.2 is hydrogen or lower alkyl; are herbicidally active compounds against grasses. Specifically disclosed weed species against which those compounds were tested are crabgrass (Digitaria adscendens), barnyardgrass (Echinochloa crus-galli), water foxtail (Alopecurus aequalis), annual bluegrass (Poa annua), green foxtail (Setaria viridis), common purslane (Portulaca oleracea), and common lambsquarters (Chenopodium album). The disclosed compounds were evaluated for their phytotoxity to broad leaved crop plants including soya bean, small red bean, sugar beet, radish and tomato. Significantly, the compounds disclosed in U.S. Pat. No. 4,447,259 patent along with certain compounds disclosed in relevant references cited therein, were evaluated on and found phytotoxic to wheat, the only cereal crop tested.
In evaluating the herbicidal activity of N-[2-(4(3,5-dichloro-2-pyridyloxy)phenoxy)propionyl] isoxazolidine, it has unexpectedly been found said compounds can be applied postemergence to cereal crops such as wheat, barley and rice, particularly wheat and rice, with substantially no phytotoxic effect while still providing excellent control of undesirable annual grasses, particularly wild oats, barnyardgrass, signalgrass, sprangletop, ryegrass and foxtails.